Number of octagonal regions in regular n-gon with all diagonals drawn.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =13a(6) =0a(7) =0a(8) =0a(9) =34a(10) =0a(11) =38a(12) =20a(13) =0a(14) =44a(15) =23a(16) =0a(17) =50a(18) =26a(19) =108a(20) =28a(21) =145a(22) =0a(23) =217a(24) =0a(25) =264a(26) =102a(27) =315a(28) =72a(29) =407